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首页> 外文期刊>Chemistry: A European journal >Iridium-Imine and -Amine Complexes Relevant to the (S)-Metolachlor Process:Structures,Exchange Kinetics,and C-H Activation by Ir~I Causing Racemization
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Iridium-Imine and -Amine Complexes Relevant to the (S)-Metolachlor Process:Structures,Exchange Kinetics,and C-H Activation by Ir~I Causing Racemization

机译：与（S）-异丙甲草胺工艺有关的铱-亚胺和-胺配合物：结构，交换动力学和Ir〜I引起外消旋的C-H活化

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Iridium complexes of DMA-imine [2,6-dimethylphenyl-l'-methyl-2'-methoxyethylimine,la) and (R)-DMA-amine [(l'R)-2,6-dimethylphen-yl-r-methyl-2'-methoxyethylamine,2 a] that are relevant to the catalytic imine hydrogenation step of the Syngenta (S)-Metolachlor process were synthesized:metathetical exchange of [Ir_2Cl_2(cod)_2] (cod = 1,5-cyclooctadiene) with [Ag(la)_2]BF_4 and [Ag((R)-2a)_2]BF_4 afforded [Ir(cod)(kappa~2-la)]BF_4 (11) and [Ir(cod)(kappa~2-(R)-2a)]BF_4 ((R)-19)),respectively.These complexes were then used in stopped-flow experiments to study the displacement of amine 2a from complex 19 by imine la to form the imine complex 11,thus modeling the product/substrate exchange step in the catalytic cycle.The data suggest a two-step associative mechanism characterized by kappa_1 = (2.6+-0.3) x10~2 M~(-1)s~(-1) and k_2 = (4.3 +- 0.6) x 10~(-2)s~(-1) with the respective activation energies E_(A1) = (7.5 +- 0.6) klmol~(-1) and E_(A2) = (37 +- 3) kJ mol~(-1).Furthermore,complex 11 reacted with H_2O to afford the hydrolysis product [Ir(cod)(eta~(6-)-2,6-dimethylaniline)]BF_4 (12),and with I_2 to liberate quantitatively the DMA-iminium salt 14.On the other hand,the chiral amine complex (R)-19 formed the optically inactive eta~6-bound compound [Ir(cod)(eta~6-rac-2a)]BF_4 (rac-18) upon dissolution in THF at room temperature,presumably via intramolecular C-H activation.This ra-cemization was found to be a two-step event with k'_1 = 9.0 x 10~(-4)s~(-1) and k_2 = 2.89 x 10~(-5)s~(-1),featuring an optically active intermediate prior to sp~3 C-H activation.Compounds 11,12,rac-18,and (R)-19 were structurally characterized by single-crystal X-ray analyses.
机译：DMA-亚胺[2,6-二甲基苯基-1'-甲基-2'-甲氧基乙基亚胺，Ia]和（R）-DMA-胺[（I'R）-2,6-二甲基苯-基-r-合成了先正达（S）-甲草胺工艺的催化亚胺加氢步骤相关的甲基-2'-甲氧基乙胺，2 a]：[Ir_2Cl_2（cod）_2]（cod = 1,5-环辛二烯）的金属交换与[Ag（la）_2] BF_4和[Ag（（R）-2a）_2] BF_4得到[Ir（cod）（kappa〜2-la）] BF_4（11）和[Ir（cod）（kappa〜2） -（R）-2a）] BF_4（（R-19-19））。然后将这些配合物用于停流实验，研究亚胺1a取代胺2a从配合物19中形成亚胺配合物11的过程。数据表明了两步缔合机理，其特征在于kappa_1 =（2.6 + -0.3）x10〜2 M〜（-1）s〜（-1）和k_2 = （4.3 +-0.6）x 10〜（-2）s〜（-1），相应的活化能E_（A1）=（7.5 +-0.6）klmol〜（-1）和E_（A2）=（37 + -3）kJ mol〜（-1）。此外，复数为11 rea用H_2O制备水解产物[Ir（cod）（eta〜（6-）-2,6-二甲基苯胺）] BF_4（12），并用I_2定量释放DMA亚胺盐14。 ，手性胺配合物（R）-19可能在室温下溶解于THF后形成光学惰性的eta-6键合化合物[Ir（cod）（eta〜6-rac-2a）] BF_4（rac-18）。通过分子内CH活化，发现这种陶瓷化是一个两步事件，k'_1 = 9.0 x 10〜（-4）s〜（-1）和k_2 = 2.89 x 10〜（-5）s〜 （-1）在sp〜3 CH活化之前具有旋光中间体。化合物11,12，rac-18和（R）-19的结构通过单晶X射线分析表征。

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